Eight university students are exploring caves. Deep in a wet part of the cave, they find an artefact with intricate patterns on it. One of the students, Laura Ainsell, touches the artefact. She can't remove her hand, and suddenly a shape begins to appear above the artefact. The Seventh Doctor and Mel are tracking "anomalous concentrations of artron energy" that have drawn the TARDIS off course. Their search leads them to a research facility in 1978 England. Baines and the other guards leave to deal with the jellyfish outside. Leech collapses, and Mel and Ly take him to the medical wing.